I recently installed a '99 Explorer intake on my 5.0 and I now have an idle problem. After hard excelleration it will not come back down to an idle, it stays around 2k rpm. I can unplug the IAC and it will idle back down to normal. I have replaced the IAC assembly, I installed a new computer, I installed a new throttle body, and I have a spacer block between the IAC and throttle body for more precise idle adjustment, but I still have the same problem. Anyone ever have this type of problem or have any tips?
High Idle Problem
- Thread starter Dangerfield23
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The first thing I did was look for vacuume leaks but so far I have not found one. However, that doesn't mean that I have not overlooked something. If I had a vacuum leak, would it idle back down if I unplug the IAC? I can unplug it and it will idle back down, but I can't drive it like that because it dies easily.
Curse
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See, that is where variances come into play. The way I often recommend setting the idle is such that the IAC is not needed to maintain a no-load, warm idle.
But based upon what you said, your IAC very well might be stuck open or maintaining too much dwell (unless...see below).
The IAC is clean? Is it installed properly (some aftermarket units install upside down, per their instructions). Was the IAC replaced as a means to alleviate this issue? If so, having two bad IAC's is not super likely. How was it with no bypass plate? That is a bit of a controlled vac leak right there, and when coupled with the puter controlled IAC duty cycle, could simulate a vac leak.
Like I said, I am sure you have thought all this through already - I am just thinking aloud with you.
Good luck.
But based upon what you said, your IAC very well might be stuck open or maintaining too much dwell (unless...see below).
The IAC is clean? Is it installed properly (some aftermarket units install upside down, per their instructions). Was the IAC replaced as a means to alleviate this issue? If so, having two bad IAC's is not super likely. How was it with no bypass plate? That is a bit of a controlled vac leak right there, and when coupled with the puter controlled IAC duty cycle, could simulate a vac leak.
Like I said, I am sure you have thought all this through already - I am just thinking aloud with you.
Good luck.
With the IAC disconected, and under no load, the idle is set perfect. The IAC is clean and installed correctly. I did replace it to help solve this problem.
I put the bypass plate on it a while back because it had an erratic idle due to the E303 cam I am running. The bypass plate fixed that problem.
I'm trying to figure out why the new intake would make it do this. When installing it, the only thing I had to do different to the electronics is move the manifold air temperature sensor to the air intake tube between the mass air meter and the throttle body. I had to do that because there was no place for it on the explorer intake.
Also, I see there is a diode on the IAC wires about 2 inches down from the plug. Perhaps if it were bad it could cause problems? It would be a coincidence that it would go bad just as soon as I put on the intake.
Thank you for the feedback.
I put the bypass plate on it a while back because it had an erratic idle due to the E303 cam I am running. The bypass plate fixed that problem.
I'm trying to figure out why the new intake would make it do this. When installing it, the only thing I had to do different to the electronics is move the manifold air temperature sensor to the air intake tube between the mass air meter and the throttle body. I had to do that because there was no place for it on the explorer intake.
Also, I see there is a diode on the IAC wires about 2 inches down from the plug. Perhaps if it were bad it could cause problems? It would be a coincidence that it would go bad just as soon as I put on the intake.
Thank you for the feedback.
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